230 THE STRUCTURE AND LIFE OF BIRDS chap. 



Flight in Troops. 



The formations adopted by birds when flying in 

 troops are very interesting, but unfortunately not much 

 is known of the subject. A wedge shape, the point 



/ \ 





Fig. 63 (after D'Esterno partly). 



Ducks in formations for troop-flying. 



The arrows in 1 and 2 represent the direction of the wind. In 1 the wash passes 

 between those to leeward ; in 2 the leeward line is too far off to feel it. In 3 (wind 

 ahead or aft or none), travelling each along his own line, they escape the wash and so 

 also in V-formation. 



leading, is the favourite, certainly among most of the 

 great water birds such as swans, cranes, and pelicans 

 (see Fig. 63). Whatever the formation, the object is 

 not that those in front may break the resistance of the 

 air for the benefit of those behind them. A bicyclist, 

 driving as he does a mass of air before him, gives 



